Hello Avinash
That is a difficult question
Because this is the matter for selection board of Euro Aqaue, which would decide upon their selection criteria which you can find on:
http://www.euroaquae.org/From the experience of other accepted students for previous years though, I can think of important issues, which can be certainly helpful for anyone joining the course, and also perhaps important for getting admission.
Having a civil engineering background is a good thing, and the higher score the better of course. One of the most important issues is language, English at first, which is critical. Knowledge of other languages of the countries involved in the course (French, German ...) would be helpful too.
It has been the case that upon your admission for the course one would get scholarship too.
Hope it is of help, but let us know if you have any other question.